Alzheimer's Disease Health Center

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Glossary of Alzheimer's Disease Terms

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Creutzfeldt-Jakob disease: A rare disorder of infectious and genetic origin that typically causes memory failure and behavioral changes. A recently identified form is thought to be due to eating meat from cattle affected by "mad cow disease."

CT scan: See computed axial tomography.

Deficits: Physical and/or cognitive skills or abilities that a person has lost, has difficulty with, or can no longer perform because of his or her dementia.

Delusion: A false idea that is firmly believed and strongly maintained in spite of contradictory proof or evidence.

Dementia: The loss of mental functions -- such as thinking, memory, and reasoning -- severe enough to interfere with a person's daily functioning. Dementia is not a disease itself, but rather a group of symptoms that may accompany certain diseases or conditions. Symptoms also may include changes in personality, mood, and behavior. Dementia is irreversible when caused by disease or injury but may be reversible when caused by drugs, alcohol, hormone or vitamin imbalances, or depression.

Dementia-capable: Skilled in working with people with dementia and their caregivers, knowledgeable about the kinds of services that may help them, and aware of which agencies and individuals provide such services.

Dementia-specific: Services that are provided specifically for people with dementia.

Depression: Low mood that prevents a person from leading a normal life and is associated with a variety of other symptoms.

Diagnosis: The process by which a doctor determines what disease a patient has by studying the patient's symptoms and medical history and analyzing results from any tests performed (blood tests, urine tests, brain scans, etc.).

Differential diagnosis: The clinical evaluation of possible causes of dementia to rule out all other factors before settling on Alzheimer's disease as a diagnosis.

Disorientation: A cognitive disability in which the person loses his/her sense of time, direction, and recognition.

DNA (Deoxyribonucleic acid): The material that controls the genetics of each cell.

Double-blind, placebo-controlled study: A research procedure in which neither researchers nor patients know who is receiving the experimental substances or treatment and who is receiving a placebo.

Down syndrome: A syndrome that causes slowed growth, abnormal facial features, and mental retardation. Down syndrome is caused by an extra copy of all or part of chromosome 21. Most individuals with Down syndrome develop Alzheimer's disease in adulthood.